John Jacob Astor arrived in Manhattan from Germany in 1784, just after the Revolutionary War. The son of a humble butcher, he became a merchant in his new nation, trading furs with Indians and starting a fur goods shop in the city by the end of the decade, while also serving as the stateside agent for his brother's musical instrument business.
By 1800, Astor had earned a quarter of a million dollars as one of the leading figures in the fur biz... But his grandest business scheme lay ahead of him.
In the mid 1700s, opium had become a popular pastime in many nations, but China, recognizing the dangers of cocaine, outlawed its sale by 1729 and by the end of the century, banned poppy trade and cultivation in the country. That didn't stop the opportunistic Astor, who, in 1816, under the guise of his fur trading business via the Br. East India Co., purchased 10 tons of Turkish opium, which he smuggled illegally into China.
The fortune he made from illegal narcotics allowed Astor to purchase a huge parcel of land in Manhattan from Aaron Burr, VP under President Thomas Jefferson, which he subdivided into 250 lots. He continued to buy—and rent—land in then-undeveloped parts of the city, just as New York's boom began moving north, which ultimately made him the wealthiest man in America by the time of his death in 1848.
Astor left an estate estimated to be worth $20 million, which today would be worth more than $110.1 billion. That's certainly nothing to sniff at, eh?